Most rules are rife with exceptions in the publishing industry, but a few are so standard and ubiquitous that they're well worth memorizing. One set of rules that are pretty standard is how to deal with numbers — whether you should spell them out or use good ole Arabic numerals.
Before you start proofreading or copyediting your text, you need to know the basic rules about incorporating numbers into narrative (nontechnical or humanistic) manuscripts and into technical (scientific) manuscripts. Definitely ask about house style for your particular project because variant, hybrid treatments are common. But a few rules are usually common to both genres and are worth committing to memory for that reason:
- Never begin a sentence with a numeral. This rule is absolute, no matter what genre you're working in. Spell out the number or reword the sentence.
- Style all numerals of the same class or type consistently in the text.
- Avoid using two unrelated numerals in a row: In 2007 40,000 people will become millionaires, and I plan on being one of them. Fix this problem by rewording the sentence: I plan on being one of the 40,000 people who will become millionaires in 2007.
- Always use a numeral before an abbreviated unit of measurement, such as 8 oz. or 7 lbs.
- Write a percentage as a numeral followed by the word percent.
Numbers in narrative documents
Narrative or nontechnical documents typically don't have many numbers in them, so the numbers are more frequently spelled out than in technical documents. You may find that these conventions hold true for most narrative projects:
- Spell out numbers from one to one hundred.
- Use numerals for page numbers, chapter numbers, years, and dates.
- Spell out large numbers only if they can be spelled out in two words: fifty-nine thousand; three million.
Numbers in technical documents
Technical documents typically have the pleasure of being rife with numbers. Hence, editors usually prefer numerals to spelled-out numbers because they're easier to find, easier to read, and less space-consuming. Here are two rules that are fairly standard in technical copyediting and proofreading:
- Spell out numbers from one to nine.
- Spell out all units of measurement.
When correcting numerals that you want spelled out, you can circle the numeral and then circle an "sp" in the margin. However, you risk that a compositor (the person preparing the laid-out text for publication) will misspell the word. It's always safer to spell the word out yourself.
